In recent years, a system has been developed, which senses a pedestrian in front of a vehicle, and warns a driver or automatically performs a braking control or a steering control to avoid a collision when a collision risk is present.
Such a vehicle front object sensing system is provided with a LIDAR sensor system that can sense a distance up to a target, a direction, a speed, a temperature, and a material of the target, and the like in order to sense the target around a vehicle, and the LIDAR sensor system emits a laser to the target and may receive information on the target through reflection light reflected on the target.
In the related art, the LIDAR sensor system is provided with a single laser emitting unit to receive the information on the target, but in recent years, a LIDAR sensor system has been researched and developed, which emits one or more lasers in order to accurately sense short-range and long-range targets of the vehicle.
However, when two lasers are emitted to the target and the reflection light reflected on the target is received, two lasers have the same polarization characteristic and thus interfere with each other.
Korean Patent Publication No. 2009-0021724 (Application date: Aug. 28, 2007) 2007.08.28)